integumentary system

• the skin is the largest organ
• skin has three layers: epidermis (outer layer), dermis (middle layer), and subcutaneous layer.
• skin protects against injury, infection, water loss, sunlight, heat, cold, and chemicals
• epidermis is the outermost layer and contains cells filled with keratin to block water and micro organisms
• dermis contains: sweat glands, oil glands, hair follicles, and blood vessels.
• subcutaneous layer serves as an insulator
• hair is made of keratin; serves as a filtering dust and protects the scalp
• nail: made out of keratin, protects fingernail and toes
• sweat glands & oil glands releases substances through pores